Silver complex diffusion transfer process separating development nuclei and alkaline liquid

ABSTRACT

Silver complex diffusion transfer reproduction process in which a liquid containing development nuclei and an aqueous alkaline liquid for diffusion transfer image formation are applied separately and in sequential order to a light-sensitive material carrying a silver halide emulsion layer after which the latter material is contacted while still moist with an image-receiving material. The photographic developing agent for the silver halide emulsion is provided via one or both of the light-sensitive and image-receiving materials so that the alkaline liquid can be free of such agent. The light-sensitive material carries a waterpermeable hydrophilic colloid layer superimposed upon the emulsion layer. The development nuclei are dispersed in the carried liquid therefor which contains only an amount of hydrophilic colloid sufficient for maintaining the nuclei in dispersion.

SILVER COMPLEX DIFFUSION TRANSFER PROCESS 'SEPARA'IING DEVELOPMENT NUCLEI AND ALKALINE LIQUID The present invention relates to a method of producing photographic images according to the silver complex diffusion transfer process. a

From United Kingdom Pat. Specifications 1,001,558 and 1,052,022 a method of producing diffusion transfer images is known, which comprises'the treatment of a light-sensitive silver halide material comprising a colloid layer on top of the silver halide emulsion layer or the treatment of both the said lightwsensitive materials and a not specially pretreated sheet material used as the receiving material with a developing or activating liquid containing development nuclei or other substance(s), which promote conversion of complexed silver halide to form a visible image. The light-sensitive and the receiving material are then pressed against each other and after an optimal contact time separated again, after which the receiving material shows the diffusion transfer image produced.

However, the method according to the said United Kingdom Pat. Specifications suffers from the following disadvantage. The keeping qualities of a processing liquid containing development nuclei together with alkaline substance(s) and occasionally also together with developing substance(s) are rather poor. Indeed, in such a medium the development nuclei cannot be kepthomogeneously dispersed during a long time and they settle quickly. The activity of many of the good development nuclei generally known in the art is thus strongly reduced and in many cases even completely eliminated in the medium involved, so that a diffusion transfer image of only.

poor quality or no image at all is obtained.

This disadvantage may be clearly avoided by proceeding according to the present invention, i.e. by making use of two separate treating liquids, viz a liquid containing development nuclei and an aqueous alkaline liquid for carrying out the diffusion transfer image formation. These two liquids are applied in the given sequence to the imagewise exposed light-sensitive material.

Thus the present invention relates to a method of producing photographicimages according to the silver complex diffusion transfer process comprising the steps of imagewise exposing a light-sensitive material comprising a silver halide emulsion layer, applying a liquid containing a substance or substances (hereinafter called development nuclei and shortly even nuclei) for promoting conversion of complexed silver halide to form a visible image, to the imagewise exposed light-sensitive material and subsequently applying an aqueous alkaline liquid for carrying through the diffusion transfer image formation, keeping the light-sensitive material in contact with a receiving material in the presence of a sufficient amount of water or other liquid to allow the transfer of the produced diffusion transfer image to the receiving material to take place, and separating the light-sensitive and the receiving material from each other, whereafter the diffusion transfer image becomes visible on the receiving material.

By proceeding according to the method of the present invention the disadvantage of the closely related method known from the prior art teaching and referred to above may be clearly avoided. The nuclei-containing liquid and the aqueous alkaline liquid are very stable and may be kept for a long time without substantial change of their characteristics. The risk of a reduction or even the complete annihilation of the action of the development nuclei is also avoided of course.

The light-sensitive material for use in carrying out the method of the present invention generally includes a suitable support sheet e.g. a paper support or a support of a synthetic polymeric material such as a support of a cellulose ester e.g. cellulose triacetate, or of polyethylene terephthalate. The silver halide emulsion layer preferably is a gelatino silver halide emulsion layer. it may be applied directly or, if necessary or advantageous, by means of a suitable subbing layer to the support sheet. Any light-sensitive emulsion composition conventionally used in the art of diffusion transfer can be used.

The emulsion composition is not critical provided its silver salt(s) is (are) capable of being developed and of diffusing in the exposed and nonexposed areas respectively with the rapidity required in diffusion transfer processes. Silver chloride emulsions are preferably used and they may contain silver bromide or silver iodine. Also silver bromide emulsions are often used, particularly when the reproduction of continuous tone originals is intended. The silver bromide emulsions may comprise minor amounts of silver iodide. It is appropriate to use the emulsion in such a way that an amount of silver halide equivalent to 0.2 to 2 of silver is present per square meter of light-sensitive material. Preferably the emulsion layer is at least slightly hardened.

The light-sensitive material for use in carrying out the method of the present invention preferably comprises a layer of a water-permeable colloid on top of the silver halide layer. Examples of water'permeable colloids, which may be used in the water-permeable colloid layer on top of the silver halide emulsion layer are: methylcellulose, the sodium salt of carboxymethylcellulose, hydroyethylcellulose, hydroxyethyl starch, hydroxypropyl starch, sodium alginate, tragacanth, starch, poly(vinyl alcohol), poly(acrylic acid), poly(acryl amide) poly(vinyl pyrrolidone), poly(oxethylene) and copoly(methylvinyl ether/maleic acid). The thickness of the water-permeable colloid top layer is selected according to i.a. the nature of the colloid applied and the viscosity of the colloid solution used. Preferably, the water-permeable colloid layer on top of the silver halide emulsion layer is unhardened or but slightly hardened.

The light-sensitive material may contain all kinds of generally used ingredients such as sensitizers, stabilizers, hardeners, occasionally latent hardeners, softening agents, latices, pigments, wetting agents, and other coating aids.

Into the light-sensitive emulsion layer and/or into at least one other water-permeable layer of the light-sensitive material a substance or substances beneficial or essential to the specific process involved, i.e. a diffusion transfer process, may be incorporated. According to a preferred embodiment developing substances are incorporated into the light-sensitive material. Suitable developing substances are 3-pyrazolidinone developing substances and hydroquinone, preferably applied together. For more details about the use of these two types of developing compounds together in the light-sensitive material, reference can be made to the U. K. Pat. Specification 1,057,273. For details on the use of developing agentsin the light-sensitive material, there can be referred to the U. K. Pat. Specifications 1,042,477, 1,054,253, 1,086,510 and to the French Pat. Specification 1,417,649. Generally a total amount of 0.1 to 5 g. of developing compound(s) is present per sq. m. of the light-sensitive material. For more details aboutsuitable coneentrations of developing compound( s) reference is made to the Patent Specifications cited hereinbefore. Other types of compounds for incorporation into the light-sensitive material and which are more or less specific to the specific process involved are preservatives for developing compounds and image-tone improving agents.

As receiving or transfer material for use in carrying out the method of the present invention there is preferably used a common paper sheet, which was not specially treated i.e. the paper sheet is not provided with a special water-permeable colloid layer. The receiving material may also have a more complex composition and comprise a suitable support sheet, e.g. a sheet of paper, film, or textile provided at the front and/or back side with at least one coating. This coating may be an impermeabilizing coating formed by a film-forming waterimpermeablc synthetic polymeric substance. Often, however, a water-permeable coating is used, e.g. a baryta coating comprising a protein binding agent such as gelatin or casein. As an alternative to barium sulfate, other pigments may be used such as kaolin or titanium dioxide, and instead of or in addition to protein binding agents polymerization products such as for instance copolymers of butadiene and styrene, poly(styrene), copolymers of vinyl chloride and vinylidene chloride,

United States Patent [72] Inventor Louis Maria De I-Iaes Edegem, Belgium [21] Appl. No. 697,005 [22] Filed Jan. 11,1968 [45] Patented Nov. 2, 1971 [73] Assignee Gevaert-Agfa, N.V.

Mortsel, Belgium [32] Priorities Jan. 11, 1967 [33] Great Britain [31] 57,642/67;

Nov. 8, 1967, Great Britain, No. 50,899/67 [541 SILVER COMPLEX DIFFUSION TRANSFER PROCESS SEPARATING DEVELOPMENT NUCLEI AND ALKALINE LIQUID 5 Claims, No Drawings [52] US Cl 96/29 [51] Int. Cl G03c 5/54 [50] Field of Search 96/29 [56] References Cited UNITED STATES PATENTS 3,223,525 12/1965 Jonker et a1. 96/48 P D 3,396,018 8/1968 Beavers et a1 96/29 Primary Examiner-Norman G. Torchin Assistant Examiner-John L. Goodrow Attorney-William J. Daniel ABSTRACT: Silver complex diffusion transfer reproduction process in which a liquid containing development nuclei and an aqueous alkaline liquid for diffusion transfer image formation are applied separately and in sequential order to a lightsensitive material carrying a silver halide emulsion layer after which the latter material is contacted while still moist with an image-receiving material. The photographic developing agent for the silver halide emulsion is provided via one or both of the light-sensitive and image-receiving materials so that the alkaline liquid can be free of such agent. The light-sensitive material carries a water-permeable hydrophilic colloid layer superimposed upon the emulsion layer. The development nuclei are dispersed in the carried liquid therefor which contains only an amount of hydrophilic colloid sufficient for maintaining the nuclei in dispersion.

containing liquid by means of a scraper or pressure rollers is often advantageous.

The aqueous alkaline liquid may be applied to the receiving material, after which the latter material may be brought in contact with the imagewise exposed light-sensitive material wetted with the nuclei-containing liquid. At this moment the development of the exposed silver halide emulsion layer and the diffusion transfer image formation start. In proceeding according to this embodiment the receiving material preferably is provided with a hydrophilic colloid layer, whereby the receiving material holds more easily a sufficient amount of the aqueous alkaline liquid for carrying through the whole method.

According to the present invention it is in general advantageous that the light-sensitive material is still wet from the application of the developing nuclei, at the very moment of applying the aqueous liquid, since the whole process is often considerably accelerated thereby.

Preferably the aqueous alkaline processing liquid is applied directly to the light-sensitive material. In doing so the total processing time may be reduced considerably and at the same time drier diffusion transfer copies are obtained, because the receiving material need not be wetted previously and can be pressed in dry condition against the light-sensitive material.

It is also possible, of course, to wet both the light-sensitive material and the receiving material with the aqueous alkaline liquid. In this way, however, the accompanying disadvantage of having a wetter difiusion transfer print is encountered generally.

Even when using pods for the application of the nuclei and the aqueous alkaline liquid the content of these pods is spread in such a manner that first the nuclei are applied to the lightsensitive material and only afterwards the aqueous alkaline liquid for carrying through the diffusion transfer image formation. For the application of the aqueous alkaline liquid the same techniques can be followed as those described above for the application of the nuclei-containing liquid.

Of course, a diffusion transfer image may also be obtained by first applying the alkaline liquid and only thereafter the development nuclei. However, by proceeding in this way there are generally obtained diffusion transfer copies of a less favorable quality. As a mater of fact, at the very moment of applying the nuclei, the development of the imagewise exposed light-sensitive silver halide emulsion layer and the diffusion of undeveloped and complexed silver halide are going on already. Owing to the initial absence of development nuclei at the surface of the silver halide emulsion layer the first diffusing complexed silver halide has the opportunity of diffusing laterally, thus resulting in an unsharp image having a fogged background.

The contact between the light-sensitive and the receiving material is effected in the presence of a sufiicient amount of water or other liquid to allow the transfer of the diffusion transfer image produced on top of the light-sensitive material to the receiving material to take place. Usually this water or other liquid comes from the wetting with the nuclei-containing liquid and/or the aqueous alkaline liquid. The keeping in contact mostly occurs by means of pressure rollers, between which both the light-sensitive and the receiving material are conducted. The receiving material may supply the aqueous alkaline processing liquid to the light-sensitive material during the contacting stage as explained above. The nuclei-containing liquid and the aqueous alkaline processing liquid may also be supplied at the contacting stage and even later by rupture of a pod or pods containing same and by uniform distribution of the contents of this pod or these pods on the surface to be processed.

After an optimal contact time the light-sensitive and the image-receiving material are separated. By supplying heat during the contact step the diffusion transfer image formation can be speeded up generally and the production of a more fastly drying diffusion transfer copy is favored. The separation of the light-sensitive material from the image-receiving material can be performed manually or by mechanical means specially designed therefor, e.g. the separating means described in the United Kingdom Pat. Specifications 1,060,572, 1,077,355, in the French Pat. Specification 1,473,494 and in the U.S. Pat. Specifications 3,297,317. Probably a thin diffusion transfer image-containing stratum is transferred during the separation stage from the light-sensitive material to the receiving material. The drying of the receiving material after separation can be accelerated, if necessary or desirable, by applying heat or by means of a blower occasionally blowing hot air.

Some or all of the individual processing steps leading to the production of the difiusion transfer copy can be carried out in a specific apparatus. Various suitable apparatus are generally known in the art. A suitable apparatus for complete processing is provided with an exposure station (the exposure may occur by transmission or reflectographically e.g. in contact and reflectographically or episcopically and reflectographically), a station for application of the nuclei-containing liquid to the light-sensitive material and a station-for the subsequent application of the aqueous alkaline processing liquid to the light-sensitive material, occasionally a unit for removing the excess of liquid, pressure rollers for bringing the light-sensitive material in contact with a preferably dry receiving material, and a unit for separating the light-sensitive material from the receiving material after production of diffusion transfer image. In the apparatus there may also be provided a transport mechanism, guidemembers, licking rollers, heating means, a blower, etc.

Particulars about exposure and development apparatus given in Progress in Photography" Vol. 1, 1940-1950, pages 76-77 and 140; vol. 11, 1951-4954, pages 156-7: vol. Ill, 1955-1958, pages 24-36, and in the patent literature cited therein, are useful in conjunction with the present invention.

According to the present invention it is also possible to use the light-sensitive material, with which there was already produced a first diffusion transfer copy, again and preferably in approximately identical conditions for the production of a second, a third, etc. diffusion transfer copy. lnthis case there is preferably used a light-sensitive material having a hydrophilic colloid layer on top of the silver halide emulsion layer.

The following examples illustrate the present invention, however, withoutlimiting same in any respect.

EXAMPLE 1 A common paper sheet weighing g. per sq. m. was coated with a gelatin silver chloride emulsion layer in such a way that per sq. m. 1.4 of hydroquinone, 0.4 g. of l-phenyl-3- pyrazolidinone, and an amount of silver chloride equivalent to 0.8 g. of silver nitrate were present.

The silver chloride emulsion layer was coated with a top layer of hydroxyethyl starch containing 0.64 g. of l-phenyl-3- pyrazolidinone per sq. m.

The lighusensitive material thus prepared was imagewise exposed reflectographically while in contact with an original. Subsequently the light-sensitive material was wetted at a rate of 4.5 cm./sec. by means of a licking roller with the following nuclei-containing liquid:

water 1000 ccs. aqueous solution of colloidal silver (trade name:

Argyrol marketed by A.C. Barnes Phlrm. Co.

Ltd., London) to g.

The light-sensitive material was then wetted immediately at the same rate of 4.5 cm./sec. by means of licking roller with the following aqueous alkaline liquid for carrying through the diffusion transfer image formation:

water 800 cca. trisodium phosphate 12 aq. 75 g. sodium sulfite anh. 40 g. sodium thiosulfate 5 sq. 10 g. water to make IOOOccs.

While still wet the light-sensitive material was pressed against a dry common paper sheet (receiving material). After a contact time of approximately 20 seconds both materials were separated again. The paper sheet showed a positive diffusion transfer image of a good quality. The diffusion transfer copy obtained was almost immediately dry.

EXAMPLE 2 A light-sensitive material as described in example 1 was imagewise exposed reflectographically while in contact with an original. Subsequently the material was conducted through the following nuclei-containing liquid in a common apparatus for producing images according to the silver complex diffusion transfer process at a rate of4.5 cm. per sec:

water I000 ccs. aqueous dispersion of nickel sulfide nuclei L944I: of gelatin and 0.598%

of nickel sulfide) l ccs.

Together with a dry common paper sheet receiving material, the light-sensitive material was then conducted immediately through a common apparatus for producing images according to the silver complex diffusion transfer process at a rate of 4.5 cm. per sec., to wet both materials with an aqueous alkaline processing liquid as described in example 1.

A diffusion transfer copy of good quality was obtained.

What we claim is:

l. A method of producing photographic images by the silver complex diffusion transfer process utilizing a light-sensitive material carrying a silver halide emulsion layer and superimposed on said emulsion layer a water-permeable hydrophilic colloid layer and an image-receiving material, at least one of said materials having a photographic developing agent for said emulsion incorporated therein, which method comprises the steps of:

a. imagewise exposing said light-sensitive material,

b. applying to said exposed light-sensitive material a liquid having development nuclei for complexed silver halide dispersed therein and containing a hydrophilic colloid in an amount not greater than required for maintaining said nuclei in dispersion,

c. subsequently applying to said light-sensitive material in the presence ofa silver halide developing agent, an aqueous alkaline liquid free of photographic developing agent for effecting diffusion transfer image formation,

d. while said light-sensitive material is moist with said aqueous alkaline liquid, contacting the same with said receiving material in substantially dry condition to cause transfer of the diffusion transfer image to said receiving material, and

e. separating the receiving material carrying the transfer image thereon from the light-sensitive material.

2. Method according to claim 1, characterized in that the receiving material is a common paper sheet.

3. Method according to claim 1, characterized in that the lightsensitive material contains hydroquinone and a 3- pyrazolidinone developing substance.

4. Method according to claim 1, characterized in that the receiving material contains hydroquinone.

5. Method according to claim 1, characterized in that each material containing a developing substance also includes a preservative for such developing substance.

i i i I 

2. Method according to claim 1, characterized in that the receiving material is a common paper sheet.
 3. Method according to claim 1, characterized in that the light-sensitive material contains hydroquinone and a 3-pyrazolidinone developing substance.
 4. Method according to claim 1, characterized in that the receiving material contains hydroquinone.
 5. Method according to claim 1, characterized in that each material containing a developing substance also includes a preservative for such developing substance. 